Recently, rapid processing of photographic materials has been keenly desired in the photographic commercial field. Satisfaction of this goal is viewed as extremely important in the industry.
Silver halides essentially comprising silver bromide, which have heretofore been mainly used in photographic materials, are in principle disadvantageous to such rapid photographic processing, since the bromide ion (which is released when the halides themselves are developed) has a development-inhibitory property. Accordingly, the use of silver halides mainly comprising silver chloride are preferred in view of speeding up the photographic processing of silver halide photographic materials.
Specifically, so-called "high silver chloride emulsions" which contain silver chloride in a high content in proportion to other silver halides are advantageous for purposes of rapid processing.
However, the use of such high silver chloride emulsions has been found to result in the following disadvantages when used for the purpose of speeding up photographic processing. More precisely, although a high silver chloride emulsion can rapidly be fixed in the desilvering step, the developed silver formed therefrom after having been developed is hardly bleached at all as compared with the developed silver formed when using a low silver chloride emulsion. This results in a disadvantage when attempting to shorten development processing which includes the desilvering step. Further, if such difficult bleachability is sought to be overcome by prolonging the desilvering time, the prolonged time will counterbalance the shortened period in the development step or, as the case may be, the prolonged time will be longer than the shortened period therein. In the desilvering step, a bleach bath and a fix bath are used in combination, or alternatively, a blix (bleach-fix) bath is used. In general, the bleaching agent to be used in the blix bath is an organic iron-chelating agent such as an aminopolycarboxylic acid/iron salt, which has the requisite oxidizing ability when used together with the fixing agent of a silver halide solvent. However, when a blix bath without strong oxidizing ability is used or, in particular, when the processing solution has been fatigued after a large amount of silver halide photographic materials have been processed therein or when the amount of the processing solution having been carried over into the bath from the previous bath has increased, the oxidizing ability of the blix bath will remarkably deteriorate, which results in a noticeable retardation of the bleaching of the developed silver. In this situation, it is often noted in some extreme cases that some parts of the developed silver from the high silver chloride emulsion still remain in their original state, almost without being desilvered at all, even after very extensive bleaching time.
In addition, shortening of the exposure time is important for the simplification of the total photographic processing procedure in order to improve overall laboratory productivity, and the emulsions to be used are required to be highly sensitive. However, it is known that high silver chloride emulsions also suffer from the disadvantages that they are easily fogged and are poor in sensitivity, although the development of such emulsions can proceed rapidly.
Silver halides generally have an intrinsic absorption range in a short wavelength range, and thus are generally spectrally sensitized so that they can absorb and be sensitive to visible rays and/or infrared rays having longer wavelengths.
However, the spectral sensitivity of a high silver chloride emulsion comprising silver chloride in an amount of 80 mol% or more is usually extremely poor even if the emulsion is spectrally sensitized with a compound which is generally applied to an emulsion essentially comprising silver bromide. In particular, this effect is even more remarkable in a high silver chloride emulsion having silver chloride in an amount of 95 mol% or more.
Moreover, it has been found that most of the spectral sensitizers described in Japanese Patent Application (OPI) Nos. 106538/83, 107531/83, 107532/83, 107533/83, 9144/83 and 95339/83 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application"), or spectral sensitizers which have generally been used for silver halides essentially comprising silver bromide, would largely inhibit bleaching of the developed silver formed from a high silver chloride emulsion.
In general, the extent of bleaching of developed silver depends not only upon the oxidizing ability of the bleaching solution, but also upon the shape or form of the developed silver, as well as the amount of the developed silver. This lesser extent of bleaching of the developed silver from a high chloride emulsion as compared to the extent of bleaching of the developed silver from a low silver chloride emulsion was determined by electron microscopic observation of the developed silver, and theorized to result from the difference of the shapes of the developed silvers therebetween.
In this connection, the more important fact is that the bleaching of the developed silver would be retarded or inhibited by any compound having been adsorbed onto the surface of the developed silver, and the extent of bleaching would also depend upon the kind of compound adsorbed. In general, most silver halide color photographic materials are constituted so as to be able to attain various functions in the respective processing steps from light-exposure to development and coloration; therefore, a variety of compounds are incorporated in the photographic materials in order to attain these respective functions. Accordingly, it is important that the photographic materials can satisfy these necessary requirements without accompanying desilvering inhibition as mentioned above.
The desilvering inhibition of the developed silver as formed from a high silver chloride emulsion was additionally observed to be caused by the presence of bromide ions, which are generally added to a color developer solution so as to maintain uniformity of development. In this case, it is assumed that bromide ions would cause the variation in the shape or form of the developed silver.
In order to solve these problems, the present inventors have conducted various studies, and as a result have determined that dyes represented by general formula (I), (II) or (III) described below can display a high spectral sensitizing ability to high silver chloride emulsions.
In particular, among these compounds cyanine dyes display a so-called J-band type spectral sensitizing ability, even in a high silver chloride emulsion containing silver chloride in an amount of 95 mol% or more, and thus, these dyes not only an an excellent J-association formability, but also an excellent adsorbability to high silver chloride grains. Further, such cyanine dyes have a high spectral sensitizing ability.
However, these dyes also show a strong adsorption to developed silver formed from a high silver chloride emulsion and thus, desilvering inhibition is observed in a general bleaching process using these cyanine dyes.